Catalanoite is an extremely rare secondary sulfate mineral found as an efflorescence in fumarolic environments. Collectors should look for delicate, needle-like white or colorless crystal aggregates that are typically highly soluble in water.
Is this catalanoite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch catalanoite with a known reference. Catalanoite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Catalanoite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Catalanoite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular crystals, efflorescent crusts.
Often confused with
Catalanoite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside catalanoite
Minerals reported to co-occur with catalanoite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₂(OH)₄(SO₄)·5H₂O
- Mohs hardness
- 2
- Density
- 1.74 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular Crystals, Efflorescent Crusts
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Volcanic Fumarole Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find catalanoite
Classic worldwide localities
- Grotte di Catalano, Sicily, Italy
Field-hunting tip
Look in volcanic fumarole deposits country, the host setting where catalanoite typically forms. If you start seeing gypsum, alunite in float, you are in the right ground. Field specimens usually show a acicular crystals, efflorescent crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find catalanoite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
